System and method for alternating-direct high voltage leak detection

ABSTRACT

A method and device for determining the existence of a leak in a package includes generating an AC high voltage with a DC high voltage offset in a circuit. A package is placed between an inspection electrode and a detection electrode, which are located within the circuit. The inspection electrode applies the AC high voltage with the DC high voltage offset to the package. Current flow through the package is then detected by the detection electrode. A detection board then processes the current flow and sends the processed signal to a programmable logic controller which determines if a leak is present in the package. If a leak is present, a signal is sent to a display to notify a user.

TECHNICAL FIELD

The invention relates to the technical field of leak detection,specifically high-voltage leak detection, methods and systemsimplementing such methods for use in detecting and signaling leaks,tears, breaks, or other imperfections in packaging containers,including, but not limited to, vials, syringes, ampoules, pouches,aluminium pouches, and I.V. bags for sensitive perishable ornon-perishable goods.

BACKGROUND OF INVENTION

There are two established techniques for using high-voltage leakdetection (HVLD) in the field of leak detection. AC high-voltage leakdetection, referred to as conventional HVLD, uses a pure AC current athigh voltage values. DC high-voltage leak detection, referred to as DCHVLD, uses a pure DC voltage at high voltage values. While bothconventional HVLD and DC HVLD employ high voltage to ultimately detectleaks, the two methods utilize very different techniques based on theinherent differences in AC and DC voltage. Because of these differenttechniques used by conventional HVLD and DC HVLD, each method hasdifferent strengths and weaknesses when it comes to testing certainpackaging containers and products contained therein.

For conventional HVLD, AC high voltage is applied to a container tobreak the resistance of the product and container. The presence of aleak is then determined by detecting the difference of the currentthrough a control container versus the current through the testedcontainer. If the difference is great enough, a leak is determined to bepresent.

The principle of conventional HVLD is shown in FIGS. 1A-1D. A controlvial 001 without defect and filled with a liquid product inspected byconventional HVLD is shown in FIG. 1A. In FIG. 1B, the testing of thecontrol vial of FIG. 1A is shown in a simplified electrical-equivalentcircuit. The testing of a defective vial 002 filled with a liquidproduct is shown in FIG. 1C being inspected by conventional HVLD. FIG.1D represents the simplified electrical equivalent circuit for thedefective vial in FIG. 1C. However it is important to note that theelectrical equivalent circuits are based on a simplified model and thatmore complex models could be created.

As shown in FIGS. 1A and 1C, conventional HVLD testing involves placinga container 007 between two electrodes 003, 005 and applying AC highvoltage 023 to the circuit, with one electrode being an inspectionelectrode 003 and the other electrode being a detection electrode 005.The two electrodes are oriented such that the container to be tested isoriented between the two electrodes without making physical contact witheither electrode. The container would then have two specific impedancesand a specific resistance: a specific impedance at the container wallacross from the inspection electrode

${R_{1} + \frac{1}{j\;\omega\; C_{1}}},$a specific impedance at the container wall across from the detectionelectrode

${R_{2} + \frac{1}{j\;\omega\; C_{2}}},$and a specific resistance of the product inside the container R_(Pro).The resulting current through the non-defective container is representedas I_(WD).

However, if the container should have a leak, a discharge current willflow through a pinhole, crack, or defective seal into the container, asshown in FIG. 1C. A leak in the container will result in the loss of oneof the impedances, as shown in FIG. 1D. The resulting current through adefective container will result in a current with different value(I_(D)) due to the loss of the specific impedance. A signal through theproduct is then detected by the detection electrode. Detecting thechange in this current enables the presence of a defect to be recognizedas follows:

$\begin{matrix}{I_{WD} = \frac{{AC}\;{HV}}{R_{Pro} + Z_{1} + Z_{2}}} & (1) \\{Wherein} & \; \\{Z_{1} = {\frac{1}{j\; 2\;\pi\;{fC}_{1}} + R_{1}}} & (2) \\{and} & \; \\{Z_{2} = {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + {R_{2}.}}} & (3)\end{matrix}$

When a leak is present one of the impedances will be missing. Thecurrent through the defective container can be found as follows:

$\begin{matrix}{I_{D} = {\frac{{AC}\;{HV}}{R_{Pro} + Z_{1}}.}} & (4)\end{matrix}$

A defective container will have a larger electric current present(I_(D)) than a container without defect (I_(WD)). The difference betweenthe electric currents determines whether the container is defective,which is shown in the following formula:ΔI=I _(D) −I _(WD)  (5).

It is important to note that the C₁, R₁, C₂, R₂, R_(Pro) are variablesand change depending on the amplitude of the applied AC high voltage,material characteristics (such as dielectric strength of the containerand liquid product), and the conductivity of the liquid product. Thehigher the applied voltage, the lower the impedances of C₁, R₁, C₂, R₂,R_(Pro). The risk of applying too large of a voltage is that appliedhigh voltage may create an arc or spark over the impedances listed aboveand cause what appears as a false leak. Therefore it is necessary inconventional HVLD technology to reach the highest possible voltage, inorder to get better sensitivity of the leak detection, without sparkingaround the container to break down the insulation of the container andthe liquid product inside the container. The risk of detecting falseleaks using the conventional HVLD is especially high withlow-conductivity products.

Beyond the risk of false-positives when used with leak detection, use ofconventional HVLD also poses risks to the integrity of the products heldwithin tested containers. The applied pure AC high voltage used inconventional HVLD is able to penetrate through the capacitive impedanceof a good container without high attenuation and expose the productwithin the container to the AC high-voltage directly. This results inpotentially harmful and unwanted exposure of the product inside of agood container to high-voltage with unknown side effects. This problemis especially important to the pharmaceutical field, where exposure tohigh voltage during testing could potentially denature or otherwise harmpharmaceutical products.

Conventional HVLD also faces mechanical disadvantages, as the componentsnecessary to create a testing device employing conventional HVLD areheavy and unwieldy. This makes a conventional HVLD benchtop toolimpractical.

Another drawbacks of the conventional HVLD is that it produces excessiveozone during an inspection since AC high voltage creates ozoneeffectively.

In DC HVLD, a container to be tested for leaks is instead charged purelywith DC high voltage. The presence of leaks is determined through thedetection of charging and neutralizing currents. The DC HVLD system ofTakeda Chemical Industries, as described in U.S. Pat. No. 4,125,805,herein after Takeda, is representative of a typical DC HVLD system.

The Takeda system uses DC high voltage to charge a container, as shownin FIG. 2. The container 105 with fluid product contained within isplaced between an anode rod 109, an auxiliary electrode rod 111, and acathode plate 107. The anode rod 109 is connected to positive side ofthe DC high voltage source 115. The cathode plate 107 and the auxiliaryrod 111 are connected to a negative side of the DC high voltage source115 through a measuring resistance 117 and a switch 119 respectively asshown in FIG. 2.

When the switch 119 is turned off, the auxiliary electrode 111 is notconnected to the negative side of the DC high voltage source 115 thenneither electrical charging nor discharging takes place. However if theswitch 119 is turned on, the auxiliary electrode 111 is connected to thenegative side of the DC high voltage source 115, and a spark dischargeoccurs between the auxiliary electrode 111 and anode rod 109 whichsimultaneously causes the electrical charge at the neck portion of theampoule 105 to be discharged. Meanwhile, a discrimination circuit 121 isused across resistor 117 to detect the potential developed across it.

A neutralizing current i₁ is caused to flow from the auxiliary electroderod 111 to the cathode plate 107, and is detected by the discriminationcircuit 121. The neutralizing current i₁ normally reaches its maximumvalue immediately after initiation of the discharge by the auxiliaryelectrode 111, and subsequently decreases rapidly, as shown in FIG. 3.In the state as described, if the ampoule is a good sample (i.e., freefrom any defects such as pin holes, etc.), with a predetermined amountof fluid contained therein, the neutralizing current (i₁) caused to flowobtains a peak value of one unit as shown in FIG. 3.

On the other hand, when the ampoule has a defect, such as a pin holelarger than 2 microns, a neutralizing current i₃ of about two units ormore is caused to flow, as shown in FIG. 3, where i₁ is the neutralizingcurrent for containers without defect and i₃ is the neutralizing currentfor containers with defect. FIG. 4 shows an equivalent circuit for theTakeda DC HVLD system shown in FIG. 2.

A major disadvantage of the DC HVLD method and system is the lack ofcontinuity and consistency in testing. In Takeda, the DC HVLD system isa discontinuous test since it is a discontinuous signal which isdiscretely created and sampled. Each package tested must be chargedbefore being discharged through the discrimination circuit for a singlemeasurement. The charging and discharging of the packages takes placeone after another. This makes using the DC HVLD system for an onlineinspection in a production line almost impossible due to its slow speedand discontinuous nature.

Another disadvantage of the DC HVLD system is the discontinuous natureof the signal applied during testing due to the charging and dischargingrequired. The high voltage discharge used in the DC HVLD system ofTakeda can be very stochastic. Since its detected signal is a discretewaveform, the signal in the DC HVLD does not have a certain frequency,phase, or amplitude. The amplitude can vary strongly dependent on theamount of charging and discharging which occurs, and can vary based onthe distance between the electrodes and the defect.

Further, the DC HVLD method requires that the anode rod is stationary attop of the package. This technology can be used only for inspection ofampoules. Containers like vials with an aluminum cap or syringes with ametal needle cannot be inspected by the DC HVLD since the metals arehighly conductive in comparison to glass or plastic and lead to falsepositive results.

DC HVLD also requires that the cathode plate is in contact with thepackage. Contact with packages during testing is undesirable for onlinetesting using rigid electrodes, as such contact is considered to be adestructive method of on-line testing.

SUMMARY OF INVENTION

The current invention solves the problem of sensitive product exposureto high voltage, undesirable levels of ozone production, andfalse-positive leak detections of conventional HVLD and the structuralinflexibility, online inspection limitations, and variability of DC HVLDby applying an AC voltage with a DC high voltage offset to a leakdetection, which can be explained by using a simplified electricalequivalent circuits in FIG. 6A to 6D, where the AC current can flowthrough all components within the circuit while the DC current can onlyflow through the path without capacitors. However it is important tonote that the electrical equivalent circuits are based on a simplifiedmodel and that more complex models could be created. Thealternating-direct high voltage (ADHV) technique includes placing acontainer to be tested between a detection electrode and an inspectionelectrode. A high voltage generation circuit is used for generating ahigh voltage, the high voltage generation circuit including a pulseautotransformer, a high voltage rectifier, and a high voltage controlboard. The container is then positioned between the inspection electrodeand the detection electrode.

High voltage, AC voltage with DC voltage offset, is then generatedthrough the high voltage generation circuit, such that an electricalcurrent is applied to the container through the inspection electrode andthe electrical current through the container is detected by thedetection electrode and processed by the detection board. The electricalcurrent through the container can be explained based on electricalequivalent circuits.

The electrical current through the container at the detection electrodeis then processed, and a leak in the container is identified through achange in electrical current through the formula ΔI=I_(D)−I_(WD),wherein,

$I_{D} = {\frac{{AC}\;{HV}}{R_{Pro} + Z_{2}} + \frac{{DC}\;{HV}}{R_{Pro} + R_{4}}}$and$I_{WD} = {\frac{{AC}\;{HV}}{R_{Pro} + Z_{1} + Z_{2}} + \frac{{DC}\;{HV}}{R_{Pro} + R_{3} + R_{4}}}$$Z_{1} = \frac{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{1}} + R_{1}} \right)*R_{3}}{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{1}} + R_{1}} \right) + R_{3}}$$Z_{2} = \frac{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right)*R_{4}}{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right) + R_{4}}$and I_(WD) is current through a container without defect, I_(D) iscurrent through a defective container. “AC HV” is the AC part ofhigh-voltage. “DC HV” is the DC offset of high-voltage. “C₁” and “R₁”are specific capacitance and resistance, respectively, of a first wallof container. “C₂” and “R₂” are specific capacitance and resistance,respectively, of a second wall of container. R₃ specific high-Ohmresistance of the first wall of container. R₄ specific high-Ohmresistance of the second wall of container. R_(Pro) specific high-Ohmresistance of liquid product inside container. “f” is frequency of AChigh voltage.

A preferred embodiment of apparatus for ADHV leak detection includes: aninspection electrode electrically connected to a high voltage rectifier;a first DC voltage power supply electrically connected to the pulseautotransformer, the pulse autotransformer further electricallyconnected to a high voltage control board, and to a high voltagerectifier; a second DC voltage power supply electrically connected tothe high voltage control board, a detection board, a programmable logiccontroller, and a display to supply them by electric power;

and a detection electrode electrically connected to a detection board,the detection board further electrically connected to the programmablelogic controller, the programmable logic controller further electricallyconnected to the display, wherein the detection electrode and theinspection electrode are positioned such that a package fits between thedetection electrode and the inspection electrode, and AC high voltagewith a DC high voltage offset is applied through the inspectionelectrode.

A preferred embodiment of a method for ADHV leak detection includes:placing a container between a detection electrode and an inspectionelectrode connected through a high voltage generation circuit forgenerating a high voltage, the high voltage generation circuit includinga pulse autotransformer, a DC voltage power supply, a high voltagerectifier, and a high voltage control board; creating a capacitiveimpedance between the product and the detection electrode and betweenthe inspection electrode and the product; generating a high voltagethrough the high voltage generation circuit, such that an electricalcurrent an electrical voltage is applied to the container through theinspection electrode and the electrical current through the container isdetected by the detection electrode and processed by the detectioncircuit; processing a change in the electrical current through thecontainer at the detection electrode; and identifying a leak in thecontainer through the change in electrical current.

A further understanding of the structural, functional, and advantageousaspects of the disclosure can be realized by reference to the followingdetailed description and drawings.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments, prior art, and examples are described, by way of exampleonly, with reference to the drawings, in which:

FIG. 1A demonstrates prior art by showing a package without defecttested using a conventional HVLD system;

FIG. 1B shows an equivalent electric circuit of the package andconventional HVLD test circuit of FIG. 1A;

FIG. 1C demonstrates prior art by showing a package with defect testedusing a conventional HVLD system;

FIG. 1D shows an equivalent electric circuit of the package with defectand conventional HVLD test circuit of FIG. 1C;

FIG. 2 demonstrates prior art by showing a representation of a DC HVLDsystem;

FIG. 3 demonstrates prior art by showing a detection signal of the DCHVLD system shown in FIG. 2;

FIG. 4 demonstrates prior art by showing an equivalent electricalcircuit of the DC HVLD system of FIG. 2;

FIG. 5 shows a representation of a preferred embodiment of the ADHV leakdetection system;

FIG. 6A shows a package without defect tested using an embodiment of theADHV system;

FIG. 6B shows an equivalent electric circuit of the package and ADHVtest circuit of FIG. 6A;

FIG. 6C shows a package with defect tested using a conventional HVLDsystem;

FIG. 6D shows an equivalent electric circuit of the package and ADHVtest circuit of FIG. 6C;

FIG. 7 shows an embodiment of an off-line ADHV leak detection systemconfigured to test a vial;

FIG. 8 shows the embodiment of an off-line ADHV leak detection system ofFIG. 7, and highlights movement of inspection and detection electrodesalong a package;

FIG. 9 shows an embodiment of an off-line ADVH leak detection systemconfigured to test a different type of vial;

FIG. 10 shows an embodiment of an off-line ADHV leak detection systemconfigured to test a different type of package, namely a syringe;

FIG. 11 shows an embodiment of an on-line ADHV leak detection system;

FIG. 12 is a graphical measurement of an AC high voltage with a DCvoltage offset through a container received at the detection electrode;

FIG. 13 is a graphical measurement of an AC high voltage with an offsetDC high voltage when applied to a package;

FIG. 14 is a graph of data collected during exposure testing ofconventional HVLD leak detection at the outside wall of a package;

FIG. 15 is a graph of data collected during exposure testing ofconventional HVLD at an internal liquid product;

FIG. 16 is a graph of data collected during exposure testing of ADHVleak detection at an internal liquid product;

FIG. 17 is a graph of data collected during exposure testing of ADHVleak detection at the outside wall of a package;

FIG. 18 is a graph of data collected during sensitivity testing ofconventional HVLD, showing both the voltage over time of a defective andnon-defective package;

FIG. 19 is a graph of data collected during sensitivity testing of ADHVleak detection testing, showing both the voltage over time of adefective and non-defective package; and

FIG. 20 shows an embodiment of an off-line ADVH leak detection systemconfigured to test a different type of package, namely a triple-pointseal gusset package.

DETAILED DESCRIPTION OF INVENTION

Various embodiments and aspects of the disclosure are described withreference to details discussed below. The following descriptions andreferenced drawings are illustrative of the disclosure and are not to beconstrued as limiting the disclosure. The drawings are not necessarilyto scale. Numerous specific details are described to provide a thoroughunderstanding of various embodiments of the present disclosure. However,in certain instances, well-known or conventional details are notdescribed in order to provide a concise discussion of embodiments of thepresent disclosure.

As used herein, the term “ADHV” is short-hand for Alternating-DirectHigh Voltage relating to the use of an AC high voltage with a DChigh-voltage offset.

As used herein, the term “electrically connected” refers to any knownmethod of connecting one or more objects or elements in an electricalcircuit such that an electrical signal or electrical current may betransmitted between the objects. Commonly, wire, cables, lines, orsimilar products are used to electrically connect one or more objects inan electrical circuit.

A preferred embodiment of a method 300 for detecting leaks in packagingincludes generating an AC high voltage with a DC high voltage offset ina circuit. A package 305 is placed between an inspection electrode 301and a detection electrode 303, which are located within the circuit. Theinspection electrode 301 applies the AC high voltage 323 with the DChigh voltage offset 329 to the package 305. Current flow through thepackage is then detected by the detection electrode. A detection boardthen processes the current flow to determine if a leak 311 is present inthe package. If a leak is present, a signal is sent to a display tonotify a user.

Multiple figures are provided to demonstrate a method of detecting aleak using the ADHV. FIG. 6A shows a package 305 without defect beingtested using the ADHV method. FIG. 6B shows an equivalent electricalcircuit representation 319 of the testing in FIG. 6A. FIG. 6C shows apackage 305 with defect being tested using the ADHV method. FIG. 6Dshows an equivalent electrical circuit representation 321 of the testingin FIG. 6C. For FIGS. 6A-6D, C1 335 represents specific capacitance of afirst wall 334 of package, R1 337 represents specific resistance of thefirst wall of package, C2 345 represents specific capacitance of asecond wall 343 of package, R2 349 represents specific resistance of thesecond wall of package, R3 339 represents specific high-Ohm resistanceof the first wall of package, R4 347 represents specific high-Ohmresistance of the second wall of package, RPro 341 represents specifichigh-Ohm resistance of liquid material inside container, f representsfrequency of AC high voltage, Lo represents ideal inductor in thesimplified equivalent circuit for blocking AC current, Co representsideal capacitor in the simplified equivalent circuit for blocking DCcurrent, Iwo represents current 307 through a container without defect,and Io represents current 309 through a defective container. It isimportant to note that the C1, R1, C2, R2, R3, R4, RPro are variablesand change depending on the amplitude of the applied AC high voltage,level of the applied DC high voltage offset, material characteristicssuch as dielectric strength of the container and liquid product, and theconductivity of the liquid product.

With both AC and DC voltages applied to the circuit, material within thepackage is only exposed to DC high voltage if a defect exists in thepackage. Typically, the package is made of an insulator which attenuatesthe applied DC high voltage strongly.

Since the ADHV method applies both AC and DC voltages, both AC and DCcurrents flow through the inspected package. In the simplifiedelectrical circuits of FIG. 6B, the AC current can flow through allcomponents in the circuit while the DC current can only flow through thepath without capacitors. The total current I_(WD) of the electricalcurrent of FIG. 6B, showing the testing of a package without defect, canbe found as sum of AC and DC currents with the following equations:

$\begin{matrix}{I_{WD} = {\frac{AC}{R_{Pro} + Z_{1} + Z_{2}} + \frac{{DC}\;{HV}}{R_{Pro} + R_{3} + R_{4}}}} & (6) \\{{wherein},} & \; \\{Z_{1} = \frac{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{1}} + R_{1}} \right)*R_{3}}{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{1}} + R_{1}} \right) + R_{3}}} & (7) \\{and} & \; \\{Z_{2} = {\frac{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right)*R_{4}}{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right) + R_{4}}.}} & (8)\end{matrix}$

Both AC and DC currents flow through a defective package, as well. Inthe simplified electrical circuits of FIG. 6D, the AC current can flowthrough all components in the circuit while the DC current can only flowthrough the path without a capacitor. The total current I_(D) of theelectrical current of FIG. 6D, showing the testing of a defectivepackage, can be found as sum of AC and DC currents with the followingequations:

$\begin{matrix}{I_{D} = {\frac{AC}{R_{Pro} + Z_{2}} + \frac{{DC}\;{HV}}{R_{Pro} + R_{4}}}} & (9) \\{{wherein},} & \; \\{Z_{2} = {\frac{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right)*R_{4}}{\left( {\frac{1}{j\; 2\;\pi\;{fC}_{2}} + R_{2}} \right) + R_{4}}.}} & (8)\end{matrix}$

If a leak is present in the package, the capacitor C₁ will be missingfrom the electrical circuit and the values of R₁ and R₃ will be zero. Anelectrical current through a defective package is therefore greater thanan electrical current through a package without defect. The differencebetween the electrical current through a defective package and theelectrical current through a package without defect enables detection ofa leak using the following equation:ΔI=I _(D) −I _(WD)  (10)wherein a leak is present if ΔI>0.

The AC high voltage with a DC high voltage offset is generated usingeither a pulse autotransformer or a pulse transformer, high voltagecontrol board, a high-voltage rectifier, and a DC voltage power supply.

The inspection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, theinspection electrode can be made of metals, conductive polymers, or anyother kind of conductive material. During application of the AC highvoltage with a DC high voltage offset, the inspection electrode can betouching the package or a small air gap can exist between the packageand the inspection electrode.

The detection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, thedetection electrode can be made of a metal, metal alloys, conductivepolymers, or any other kind of conductive material. During detection ofthe current produced with the AC high voltage with a DC high voltageoffset, the detection electrode can be touching the package or a smallair gap can exist between the package and the detection electrode.

The package can be in the form of a vial, a syringe, an ampoule, apouch, a bag, a blow-seal, and any other kind of container made ofplastic, glass, aluminum foils, or any other kind of material suitableto be filled with medicinal, food, or similar perishable or sensitiveproduct.

In another embodiment of a method for detecting leaks in packaging, anAC high voltage with a DC high voltage offset is generated in a circuit.A package is placed between an inspection electrode and a detectionelectrode, which are located within the circuit. The package is rotatedalong a single axis between the inspection electrode and the detectionelectrode. Further, the inspection electrode and detection electrodemoved along the length of the package as the package is rotated. Theinspection electrode applies the AC high voltage with the DC highvoltage offset to the package. Current flow through the package is thendetected by the detection electrode. A detection board then processesthe current flow to determine if a leak is present in the package usingthe same equations as the preferred embodiment. If a leak is present, asignal is sent to a display for a user to visualize.

The AC high voltage with a DC high voltage offset is generated usingeither a pulse autotransformer or a pulse transformer, high voltagecontrol board and a high-voltage rectifier.

The inspection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, theinspection electrode can be made of metals, conductive polymers, or anyother kind of conductive material. During application of the AC highvoltage with a DC high voltage offset, the inspection electrode can betouching the package or a small air gap can exist between the packageand the inspection electrode.

The detection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, thedetection electrode can be made of a metal, metal alloys, conductivepolymers, or any other kind of conductive material. During detection ofthe current produced with the AC high voltage with a DC high voltageoffset, the detection electrode can be touching the package or a smallair gap can exist between the package and the detection electrode.

The package can be in the form of a vial, a syringe, an ampoule, apouch, and any other kind of container made of plastic, glass, aluminumfoils, or any other kind of material suitable to be filled withmedicinal, food, or similar product.

A further embodiment of the method includes generating an AC highvoltage with a DC high voltage offset in a circuit. A package is placedon a conveyor. The conveyor moves the package between an inspectionelectrode and a detection electrode, which are located within thecircuit. The inspection electrode applies the AC high voltage with theDC high voltage offset to the package. Current flow through the packageis then detected by the detection electrode. A detection board thenprocesses the current flow to determine if a leak is present in thepackage using the same equations as the preferred embodiment. If a leakis present, a signal is sent to a display for a user to visualize.

The AC high voltage with a DC high voltage offset is generated usingeither a pulse autotransformer or a pulse transformer, a high-voltagerectifier and a DC voltage power supply.

The inspection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, theinspection electrode can be made of metals, conductive polymers, or anyother kind of conductive material. During application of the AC highvoltage with a DC high voltage offset, the inspection electrode can betouching the package or a small air gap can exist between the packageand the inspection electrode.

The detection electrode can be rigid, semi-rigid, or flexible in theform of a brush, a rod, steel, or similarly shaped object. Further, thedetection electrode can be made of a metal, metal alloys, conductivepolymers, or any other kind of conductive material. During detection ofthe current produced with the AC high voltage with a DC high voltageoffset, the detection electrode can be touching the package or a smallair gap can exist between the package and the detection electrode.

The package can be in the form of a vial, a syringe, an ampoule, apouch, a bag, a blow-seal, and any other kind of container made ofplastic, glass, aluminum foils, or any other kind of material suitableto be filled with medicinal, food, or similar perishable or sensitiveproduct.

There are many embodiments of a device for applying the ADHV testingmethod. Such embodiments vary based on the types of packages to betested and whether packages are to be tested one at a time, also knownas off-line testing, or if multiple packages are to be testedcontinuously without user manipulation, also known as on-line testing.

As shown in FIG. 5, a preferred embodiment of a leak detection circuit200 includes an inspection electrode 201 connected to high voltagerectifier 205 by a high voltage cable 203, the high voltage rectifierfurther electrically connected to a pulse autotransformer 208, a firstDC voltage power supply 209 electrically connected to the pulseautotransformer 208, the pulse autotransformer electrically connected toa high voltage control board 211, the high voltage control board 211electrically connected to a programmable logic controller 217, adetection electrode 227 connected to a detection board 219 via ashielded cable 225, the detection board electrically connected to theprogrammable logic controller, a display 215 electrically connected tothe programmable logic controller, a secondary DC power supply 213electrically connected to the high voltage control board 211, thedetection board 219, the programmable logic controller 217, and thedisplay 215, wherein the detection electrode 227 and the inspectionelectrode 201 are positioned such that a package 202 fits between thedetection electrode 227 and the inspection electrode 201 and AC highvoltage with a DC high voltage offset is applied to the package oncepositioned between the inspection electrode 201 and detection electrode227. The AC high-voltage with a DC high-voltage offset may be generatedby a means known in the art other than the pulse autotransformer 208with a DC voltage power supply 213, a high-voltage rectifier 205, and ahigh voltage control board 211, such as, but not limited to, a pulsetransformer 208 with a DC voltage power supply 213, a high-voltagerectifier 205, and a high voltage control board 211. In such a case theinspection electrode 201 is electrically connected to the high-voltagerectifier 205, which is electrically connected to the pulse transformer208.

Either the combination of the DC power supply 209, the high voltagecontrol board 211, and the high voltage pulse autotransformer 208 or thecombination of the DC power supply 209, the high voltage control board211, and pulse transformer 208 generate AC high voltage.

The high voltage control board 211 can be, but is not limited to,combination of microprocessor and a MOSFET or IGBT. The microprocessorturns the MOSFET or IGBT on and off by generating pulses with certainduration and duty cycle which switches the current flow from the DCpower supply 209 through the high voltage pulse autotransformer 208 orthe high voltage pulse transformer 208 on and off. Since the currentthrough the high voltage pulse autotransformer 208 or the high voltagepulse transformer 208 switched on and off AC high voltage is generatedat outputs of the high voltage pulse autotransformer 208 or the highvoltage pulse transformer 208. The high voltage control board 211adjusts the amplitude of the generated AC high voltage by changing theduration and the duty cycle of the pulses.

The high voltage rectifier 205 rectifies the AC high voltage andprovides a DC offset to the AC high voltage. The AC high voltage with DCoffset is applied to the package through the high voltage cable 203 andinspection electrode 201.

Once AC high voltage with DC high voltage offset is applied to thepackage 202 via the inspection electrode 201, the detection electrode227 receives the resulting current through the package 202. The currentthen travels to a current detection board 219, where the current isprocessed to determine whether or not a leak is present.

The detection board 219 is electrically connected in to the programmablelogic controller 217. The detection board 219 processes the receivedsignal and sends the processed signal to the programmable logiccontroller 217 and the display shows whether a leak is present. Theprogrammable logic controller 217 is electrically connected to thecurrent detection board 219, such that the programmable logic controller217 can be programed to interact with the detection board 219 in thedesired manner. The programmable logic controller 217 is furtherelectrically connected to the high voltage control board 211 such thatthe programmable logic controller 217 can be programed to interact withthe high voltage control board 211 in the desired manner. The display215 is electrically connected to the programmable logic controller 217to provide information stored in the programmable logic controller to auser, including audio and visual information. The second DC voltagepower supply is connected to the high voltage control board 211, thedetection board 219, programmable logic controller 217, and display 215to supply them by electrical power.

The AC high-voltage with a DC high-voltage offset may generated by ameans known in the art other than the pulse autotransformer 207 with theDC voltage power supply 209, the high voltage control board 211, and thehigh-voltage rectifier 205, such as, but not limited to, a pulsetransformer 208 with the DC voltage power supply 209, the high voltagecontrol board 211, and the high-voltage rectifier 205. In such a casethe inspection electrode 201 is electrically connected to thehigh-voltage rectifier 205, which is electrically connected to the pulseautotransformer 207 or the pulse transformer 208.

The package 202 may be a vial, a syringe, an ampoule, or other similarpouch, bottle, container, or sealed holder. Further, the package 202 canbe made of plastic, glass, or another material which exhibits capacitiveand resistive properties. The package is filled with product typically,but not exclusively, including food, medicinal, biological, or othersimilar products. A holder may be used to secure the package 202 duringtesting. The holder may include, but is not limited to, a tray, a rodwith securing mechanism, a belt, or other similar device. Additionally,the holder may be attached to a rotation mechanism that rotates theholder and the package between the inspection and detection electrodes.

Both the inspection electrode 201 and detection electrode 227 can beshaped differently and made of different materials depending on theirapplication. The inspection electrode 201 and detection electrode 227can be made of a metal, metal alloys, conductive polymers, magneticmaterials, or any other kind of conductive material. The inspectionelectrode 201 and detection electrode 227 can be rigid, semi-rigid, orflexible, and in the form of a brush, a rod, a comb, or a similarlyshaped object. During application and detection of the current producedwith the AC high voltage with a DC high voltage offset, both theinspection electrode 201 and detection electrode 227 can be touching thepackage 202. Conversely, a small air gap 204 can exist between thepackage 202 and the inspection electrode 201 and detection electrode227. The small air gap 204 can be between the inspection electrode 201and the package, and the detection electrode 227 and the package 202.The small air gap 204 can be between 0.2 mm to 5 mm wide. The inspectionelectrode 201 and detection electrode 227 should not touch each otherduring testing, and they should be positioned far enough apart toprevent arcing.

The inspection electrode 201 and detection electrode 227 may also bemovable in relation to the package. A sliding mechanism can be attachedto either or both of the inspection electrode and detection electrode.The sliding mechanism can move along the length of the package andtowards or away from the package. This movement allows the electrodes tobe moved apart during placement and removal of the package from betweenthe inspection electrode and the detection electrode. The movementafforded by the sliding mechanism also allows the inspection electrodeand detection electrode to maintain contact with, or an even distancefrom, a package with slopes, curves or irregular shapes during testing.

A conveyor may also be used in conjunction with leak detection circuit200 for on-line testing. One or more packages are placed on theconveyor, which moves the package between the inspection electrode 201and the detection electrode 227. Depending on the type of package to betested, the inspection electrode 201 and detection electrode 227 may beconfigured to touch the package 202 during testing or be spaced toprovide an air gap between the electrodes 201 and 227 and the package202. The conveyor can be structured in any way which would permit theinspection electrode 201 be positioned in such a way to apply an AC highvoltage with DC high voltage offset to one surface of the package 202and permit the detection electrode 227 to be positioned to receive theresulting current at an opposing surface of the package 202. FIG. 11provides an example of one possible embodiment of the leak detectioncircuit 200 coupled with a conveyor. The conveyor in FIG. 11 is a seriesof rollers where a detection electrode is positioned between two rollersand an inspection electrode hangs above the conveyor. Another viableorganization would be a conveyer system with two belts. The electrodes201 and 227 are placed between the two conveyer belts at a certaindistance from each other to prevent a direct spark between theelectrodes. Use of a conveyor with the leak detection system 200 doesnot otherwise limit the structural variety of the elements of thepreferred embodiment discussed.

FIG. 7 shows another embodiment of a leak detection system 400,specifically at a testing interface 402 where a package 409 is securedbetween an inspection electrode 401 and a detection electrode 403. Aholder 411 secures the package 409, shown in this embodiment as a vial,horizontally during testing. A rotation mechanism 413 spins the holder411 and the package 409 coaxially during testing. The inspectionelectrode 401 and the detection electrode 403 do not touch the package409 in this embodiment to prevent scratching or marking of the package409 during testing.

An inspection sliding mechanism 417 is attached to the inspectionelectrode 401. The inspection sliding mechanism 417 allows theinspection electrode 401 to move horizontally back and forth along thelength of the package 409 during testing. A detection sliding mechanism415 is attached to the detection electrode 403. The detection slidingmechanism 415 allows the detection electrode 403 to move horizontallyback and forth along the length of the package 409 during testing.

FIG. 8 shows the same embodiment of the leak detection system 400.However, FIG. 8 demonstrates the positioning of the inspection electrode401 and the detection electrode 403 achievable when attached to theinspection sliding mechanism 417 and detection sliding mechanism 415,respectively. Where FIG. 7 shows the inspection electrode 401 anddetection electrode 403 centered, FIG. 8 shows the electrodes 401 and403 offset as a representation of sliding mechanisms 415 and 417 abilityto slide the electrodes 401 and 403 back and forth along the length ofthe package 409 during testing.

A high voltage cable 405 connects the inspection electrode 401 of theembodiment shown in FIG. 7 to the remaining elements of the leakdetection circuit 200 as described in the preferred embodiment and shownin FIG. 5. Likewise, the shielded cable 407 connects the detectionelectrode 403 to the remaining elements of the leak detection circuit200 as described in the preferred embodiment and shown in FIG. 5.

FIG. 9 shows another embodiment of a leak detection system 500,specifically at a testing interface 502 where a package 505 is securedbetween an inspection electrode 501 and a detection electrode 503. Aholder 517 secures the package 505, shown in this embodiment as a vial,horizontally during testing. A rotation mechanism 519 spins the holder517 and the package 505 coaxially during testing. A tray 515 ispositioned below the package 505. The inspection electrode 501 and thedetection electrode 503 again do not touch the package 505 in thisembodiment to prevent scratching or marking of the package 505 duringtesting.

An inspection sliding mechanism 509 is attached to the inspectionelectrode 501. The inspection sliding mechanism 509 allows theinspection electrode 501 to move horizontally back and forth along thelength of the package 505 during testing. A detection sliding mechanism507 is attached to the detection electrode 503. The detection slidingmechanism 507 allows the detection electrode 503 to move horizontallyback and forth along the length of the package 505 during testing. Theelectrodes 501 and 503 are offset in FIG. 9 as a representation of theability of the sliding mechanisms 507 and 509 to slide the electrodes501 and 503 back and forth along the length of the package 505 duringtesting. The remaining elements, their variations, and structuralcooperation are as described in the preferred embodiment.

A high voltage cable 511 connects the inspection electrode 501 of theembodiment shown in FIG. 9 to the remaining elements of the leakdetection circuit 200 as described in the preferred embodiment and shownin FIG. 5. Likewise, the shielded cable 513 connects the detectionelectrode 503 to the remaining elements of the leak detection circuit200 as described in the preferred embodiment and shown in FIG. 5. Theremaining elements, their variations, and structural cooperation are asdescribed in the preferred embodiment.

FIG. 10 shows yet another embodiment of a leak detection system 600,specifically at a testing interface 602 where a package 613 is securedbetween an inspection electrode 601 and a detection electrode 603. Aholder 609 secures the package 613, shown in this embodiment as syringe,horizontally during testing. A rotation mechanism 611 spins the holder609 and the package 613 coaxially during testing. A tray 615 ispositioned below the package 613. The inspection electrode 601 and thedetection electrode 603 again do not touch the package 613 in thisembodiment to prevent scratching or marking of the package 613 duringtesting.

An inspection sliding mechanism 605 is attached to the inspectionelectrode 601. The inspection sliding mechanism 605 allows theinspection electrode 601 to move horizontally back and forth along thelength of the package 613 during testing. A detection sliding mechanism607 is attached to the detection electrode 603. The detection slidingmechanism 607 allows the detection electrode 603 to move horizontallyback and forth along the length of the package 613 during testing. Theelectrodes 601 and 603 are at similar relative positions in FIG. 10, butare capable of sliding along the length of the package 613 independentlyas described in previous embodiments.

The inspection electrode 601 of the embodiment shown in FIG. 10 isconnected to the remaining elements associated with the leak detectioncircuit 200 as described in the preferred embodiment and shown in FIG.5. Likewise, the detection electrode 603 is connected to the remainingelements associated with the leak detection circuit 200 as described inthe preferred embodiment and shown in FIG. 5. The remaining elements,their variations, and structural cooperation are as described in thepreferred embodiment.

FIG. 11 shows a conveyor embodiment of a leak detection system 700,specifically at a testing interface 702 where a package 709 deliveredbetween one or more inspection electrodes 701 and a detection electrode703 via a conveyor 707. The conveyor 707 provides the same function asthe holder in previous embodiments of securing the package 709, shown inthis embodiment as a non-rigid IV bag, between the inspection electrode701 and the detection electrode 703. As with the preferred embodiment,the conveyor embodiment show in FIG. 11 could be used to test packagesof other shapes, size, materials, and designs, including but not limitedto vials, ampoules, syringes, pouches, and similar containers. Further,as with the preferred embodiment, the inspection electrode 701 anddetection electrode 703 need not be limited to only brushes and mayinclude the variations provided in the preferred embodiment.

In this embodiment, the inspection electrode 701 and the detectionelectrode 703 are brushes, instead of rods, as shown in previousembodiments. The inspection electrode 701 and the detection electrode703 contact the package 709 at opposing surfaces of the package 709 asthe conveyor 707 passes the package 709 between the two electrodes 701and 703. The electrodes 701 and 703 are spaced far enough apart fromeach other as to prevent arcing during testing.

An electrode sliding mechanism 705 is attached to the inspectionelectrode 701. The electrode sliding mechanism 705 allows the inspectionelectrode 701 to move back and forth along the width of the conveyor 707during testing. While not shown in FIG. 11, a similar electrode slidingmechanism can be attached to the detection electrode 703 to allow thedetection electrode to slide back and forth along the width of theconveyor 707 during testing.

The inspection electrode 701 of the embodiment shown in FIG. 11 isconnected to the remaining elements associated with the leak detectioncircuit 200 as described in the preferred embodiment and shown in FIG.5. Likewise, the detection electrode 703 is connected to the remainingelements associated with the leak detection circuit 200 as described inthe preferred embodiment and shown in FIG. 5. The remaining elements,their variations, and structural cooperation are as described in thepreferred embodiment.

FIG. 20 shows yet another embodiment of a leak detection system 800,specifically at a testing interface 802 where a package 813 is securedbetween an inspection electrode 801 and a detection electrode 803. Atray 815 is positioned below the package 813 to secure the packageduring testing. The inspection electrode 801 and the detection electrode803 again do not touch the package 813 in this embodiment to preventscratching or marking of the package 813 during testing.

An inspection sliding mechanism 805 is attached to the inspectionelectrode 801. The inspection sliding mechanism 805 allows theinspection electrode 801 to move horizontally back and forth along thelength of the package 813 during testing. A detection sliding mechanism807 is attached to the detection electrode 803. The detection slidingmechanism 807 allows the detection electrode 803 to move horizontallyback and forth along the length of the package 813 during testing. Theelectrodes 801 and 803 are at similar relative positions in FIG. 20, butare capable of sliding along the length of the package 813 independentlyas described in previous embodiments.

In this embodiment 800, the package 813 primary tested is a gussetpouch, or a package that has a triple seal point. The inspectionelectrode 805 is placed under the gusset of the pouch and its pointtouches the triple seal point of the package from the gusset side.

The inspection electrode 801 of the embodiment shown in FIG. 20 isconnected to the remaining elements associated with the leak detectioncircuit 200 as described in the preferred embodiment and shown in FIG.5. Likewise, the detection electrode 803 is connected to the remainingelements associated with the leak detection circuit 200 as described inthe preferred embodiment and shown in FIG. 5. The remaining elements,their variations, and structural cooperation are as described in thepreferred embodiment. The package is filled with medicinal, food, orother product is placed in a tray 815 so that it sits upright.

EXAMPLES Example 1 Conventional HVLD Exposure

In any HVLD technology it is necessary to reach the highest possiblevoltage to produce a high signal response from a defect, withoutsparking around the container to break down the insulation of thecontainer and the liquid product inside the container, while stillaiming to make the container conductive to get better sensitivity of theleak detection.

In the case where a conventional HVLD technology is used for leakdetection, the applied pure AC high-voltage is able to penetrate throughthe capacitive impedance of a good container without high attenuationand expose the product within the container to the AC high-voltagedirectly. This results in potentially harmful and unwanted exposure ofthe product inside of a good container to high voltage with potentiallynegative side effects.

To determine how much voltage that the product inside a container isexposed to during a conventional HVLD inspection, a 15 mL vial was putunder 18.5 kV_(Pk) AC high-voltage and the voltage inside the containerwas measured. The vial was without defect and filled with tap water. ATektronix P6015A high-voltage probe with 1:1000 ratio and a TektronixTDS2024 oscilloscope were used for this measurement. Conductivity of thetap water was 87.5 uS. A voltage measurement probe was located on theinside wall of the vial close to a pointed inspection electrode. FIG. 15shows the measured voltage of the water inside the vial during aninspection by the conventional HVLD system. FIG. 14 shows the measuredvoltage applied at the outside wall of the vial during testing by theconventional HVLD, which was 18.5 kV_(Pk). Tektronix P6015A high-voltageprobe with 1:1000 ratio and Tektronix TDS2024 oscilloscope was used forthis measurement.

The measured voltage of the tap water inside the vial was around 7kV_(Pk), shown in FIG. 15. This experiment result shows that thesensitive medicinal products inside the vials were directly exposed toextremely high voltage when inspected by the conventional HVLD system.The effect of this high voltage on product within the vial variesdepending on heat sensitivity or other factors.

Example 2 ADHV Exposure

One of the main advantages of ADHV testing over the conventional HVLDtechnology is that the product inside the containers is not exposed tohigh voltage directly. The syringes, vials, and other containers aremade of glass or plastic. Glass and plastic are electrical insulatorsthat are capacitive in nature and therefore inherently fully block, orattenuate, the DC high voltage stronger than an AC high voltage of thesame amplitude. The product inside containers are either completelyinsulated from the DC high voltage offset or are only exposed to arelatively low DC voltage. The product is only exposed to the DC highvoltage in presence of a leak or leaks in the container.

To prove that the product inside the containers are not exposed tohigh-voltage during an inspection by ADHV, the same sample used inExample 1 with conventional HVLD system, a 15 mL vial filled with tapwater, was tested. Conductivity of the tap water was 87.5 uS. The peakamplitude of voltage applied in the ADHV system was −18.5 kV_(Pk).

The experimental vial was without defect. Tektronix P6015A high-voltageprobe with 1:1000 ratio and Tektronix TDS2024 oscilloscope was used forthis measurement.

The measured ADHV voltage when the ADHV was applied to the outside wallof the vial is shown in FIG. 18. It can be seen from this figure thatamplitude of the AC component is around 5 kV_(PP) and the DC highvoltage offset is around −16 kV. Tektronix P6015A high-voltage probewith 1:1000 ratio and Tektronix TDS2024 oscilloscope was used for thismeasurement.

As shown in FIG. 16, measured voltage of the product inside the vialduring an inspection by HVLD technology based on ADHV was approximately−300V_(Pk). The voltage measurement probe was located on the inside wallof the vial close to the inspection electrode. Tektronix P6015A voltageprobe with 1:1000 ratio and Tektronix TDS2024 Oscilloscope was used forthis measurement.

The test results show that the product, in this case tap water, is notexposed to high-voltage during an inspection by the ADHV technology whenno defect is present. The high DC voltage was strongly attenuated by thecapacitive impedance of the container. In comparison to this result, themeasured voltage inside the vial in conventional HVLD system was 7kV_(Pk). In summary, HVLD technology based on an ADHV is the only HVLDmethod used in the pharmaceutical and biotechnology industry that can betruly nondestructive.

Example 3 Ozone Production

Another important advantage of the HVLD technology based on an ADHV isthat it produces much less ozone than the conventional HVLDtechnologies. The amount of ozone produced by the ADHV method isnegligible in comparison to the amount of ozone produced by theconventional HVLD method. An experiment was performed to determine howmuch ozone the conventional HVLD systems produce during an inspection incomparison to the HVLD technology based on an ADHV. A calibratedAeroqual 200 Series ozone detector with 0.001 ppm resolution was placedinside the test chamber of both systems. Both systems were hermeticallysealed.

The AC high-voltage amplitude in the conventional HVLD system was set at18.5 k V_(Pk). The AC high-voltage was turned on for five minutes. Theozone detector detected 0.150 ppm ozone inside the chamber at the end ofthe test.

The high-voltage amplitude at the ADHV system was set at −18.5 k V_(Pk)and was turned on for five minutes. Ozone inside the chamber was 0.004ppm at the end of the test.

This experiment shows that the ADHV system is a much safer inspectiontool in terms of ozone production during operation compared with theconventional HVLD systems. This is especially important when HVLDsystems are run on-line continuously on a conveyor belt, as the HLVD isconsistently producing ozone around workers in such a setting.

Example 4 Sensitivity

ADHV has higher sensitivity than the conventional HVLD systems fordetection of leaks in containers filled with low-conductivity aqueousproducts. FIG. 12 shows a graphical representation of ADHV voltagedetected at the detection electrode during an inspection of a syringewithout defect filled with tap water. The conductivity of the water was87.5 uS. FIG. 13 shows a graphical representation of ADHV currentapplied to a container.

An experiment was performed by using identical samples to determine andcompare the sensitivities of the two systems. A 1 mL syringe with defectand a 1 mL syringe without defect were tested. The defective syringe hada 2-micron laser-drilled pinhole which was made and certified by LenoxLaser.

For the testing of the conventional HVLD system, the high voltage wasset at 12 kV_(Pk). The results of the conventional HVLD system are shownin FIG. 18. The solid line shows the signal for the defective syringe,and the broken line shows the signal for the syringe without defect. Thevoltage set was 12 kV_(Pk). The syringes were rotated at 320 rpm. Thedetected signal was around 3.6V for the syringe without defect and 5.4Vfor the defective syringe. The ratio of the signal levels for syringeswith and without defect was 5.4V/3.6V=1.5.

For the testing of the ADHV system, voltage was set at −12 kV_(Pk). 1 mLsyringes with and without defect were tested by the ADHV system. Asshown in FIG. 19, the solid line represents the syringe with defect. Thebroken line shows the signal for the syringe without defect. Unlike theconventional HVLD system, the solid line of the ADHV system alsonotifies the location of the leak, which is the position of maximumamplitude of the signal. The high voltage was set at −12 kV_(ρk). Bothsyringes tested were rotated at 320 rpm. The detected signal for thesyringe without defect was 2.2V and 7.7V for the defective syringe. Theratio of the signal levels for the defective syringe to the syringewithout defect was 7.7V/2.2V=3.5.

This experiment shows that the ADHV technology is more than twice assensitive as the conventional HVLD technology, and precisely locates theleak and or leaks, which is not the case with a conventional HVLDtechnology.

The invention claimed is:
 1. A leak detection apparatus using an ACvoltage with a DC high voltage offset comprising: an inspectionelectrode electrically connected to a high voltage rectifier; the highvoltage rectifier further electrically connected to a pulseautotransformer or by other means of creating an AC voltage with a DChigh voltage offset; a first DC voltage power supply electricallyconnected to the pulse autotransformer, the pulse autotransformerfurther electrically connected to a high voltage control board, whereinthe pulse autotransformer receives direct current from the first DCvoltage power supply and generates pulsed direct current from the directcurrent; a second DC voltage power supply electrically connected to thehigh voltage control board, a detection board, a programmable logiccontroller, and a display, wherein the second DC voltage power supply isconfigured to supply electrical power to the high voltage control board,the detection board, the programmable logic controller, and the display;a detection electrode electrically connected to the detection board, thedetection board further electrically connected to the programmable logiccontroller, the programmable logic controller further electricallyconnected to the display; wherein the detection electrode and theinspection electrode are positioned such that a package fits between thedetection electrode and the inspection electrode, and the AC voltagewith the DC high voltage offset is applied through the inspectionelectrode, wherein the high voltage rectifier generates the AV voltagewith the DC high voltage offset from the pulsed direct current generatedby the pulse autotransformer via the direct current received from thefirst DC voltage power supply.
 2. The apparatus of claim 1, wherein: thehigh voltage control board can be, but is not limited to, combination ofmicroprocessor and a MOSFET or IGBT; the microprocessor turns the MOSFETor IGBT on and off by generating pulses with certain duration and dutycycle which switches current flow from the first DC power supply throughthe high voltage pulse autotransformer on and off; the switching on andoff of the direct current through the high voltage pulse autotransformergenerates an AC high voltage at outputs of the high voltage pulseautotransformer; the high voltage control board adjusts amplitude of thegenerated AC high voltage by changing the duration and the duty cycle ofthe pulses generated by the microprocessor.
 3. The apparatus of claim 1,further comprising: a holder, wherein the holder secures the packagebetween the inspection electrode and the detection electrode duringtesting.
 4. The apparatus of claim 1, wherein the holder rotates thepackage along an axis during testing.
 5. The apparatus of claim 1,wherein the inspection electrode and detection electrode are movablealong the length of the package during testing.
 6. The apparatus ofclaim 1, wherein a pulse transformer and the high voltage rectifier areused to generate the AC high voltage with the DC high voltage offsetinstead of the pulse autotransformer and the high voltage rectifier. 7.The apparatus of claim 1, further comprising: a conveyor system, whereinmultiple packages are tested without user interference by a conveyorautomatically moving packages between the inspection electrode and thedetection electrode.
 8. The apparatus of claim 1, wherein: the detectionelectrode detects an electrical current and transmits the electricalcurrent to the detection circuit; the detection circuit processes theelectrical current and sends the processed signal to the programmablelogic controller; the programmable logic controller processes a changebetween the measured electrical current and a non-defective electricalcurrent; the programmable logic controller identifies a leak in thecontainer through the change in electrical current; and the displaypresents results of test.
 9. The apparatus of claim 8, wherein thechange in the electrical current ΛI is calculated by ΛI=_D−I_WD, whereinID is a current for a defective container and IWD is a current for acontainer without defect,I_D=AC/(R_Pro+Z_2)+(DC HV)/(R_Pro+R_4),wherein,Z_2=((1/(j2πfC_2)+R_2)*R_4)/((1/(j2π[(fC)]_2)+R_2)+R_4), andI_WD=AC/(R_Pro+Z_1+Z_2)+(DC HV)/(R_Pro+R_3+R_4), whereinZ_1=((1/(j2πfC_1)+R_1)*R_3)/((1/(j2π[(fC)]_1)+R_1)+R_3), andZ_2=((1/(j2πfC_2)+R_2)*R_4)/((1/(j2π[(fC)]_2)+R_2)+R_4).
 10. A leakdetection apparatus using an AC voltage with a DC high voltage offsetcomprising: an inspection electrode electrically connected to a highvoltage rectifier; the high voltage rectifier further electricallyconnected to a pulse autotransformer or by other means of creating an ACvoltage with a DC high voltage offset; a first DC voltage power supplyelectrically connected to the pulse autotransformer, the pulseautotransformer further electrically connected to a high voltage controlboard; a second DC voltage power supply electrically connected to thehigh voltage control board, a detection board, a programmable logiccontroller, and a display, wherein the second DC voltage power supply isconfigured to supply electrical power to the high voltage control board,the detection board, the programmable logic controller, and the display;a detection electrode electrically connected to the detection board, thedetection board further electrically connected to the programmable logiccontroller, the programmable logic controller further electricallyconnected to the display, wherein the detection electrode detects anelectrical current and transmits the electrical current to a detectioncircuit, wherein the detection circuit processes the electrical currentand sends the processed signal to the programmable logic controller,wherein the programmable logic controller processes a change between themeasured electrical current and a non-defective electrical current,wherein the programmable logic controller identifies a leak in thecontainer through the change in electrical current, wherein the displaypresents results of test; wherein the detection electrode and theinspection electrode are positioned such that a package fits between thedetection electrode and the inspection electrode, and the AC voltagewith the DC high voltage offset is applied through the inspectionelectrode, wherein the change in the electrical current ΛI is calculatedby ΛI=_D−I_WD, wherein ID is a current for a defective container and IWDis a current for a container without defect,I_D=AC/(R_Pro+Z_2)+(DC HV)/(R_Pro+R_4),wherein,Z_2=((1/(j2πfC_2)+R_2)*R_4)/((1/(j2π[(fC)]_2)+R_2)+R_4), andI_WD=AC/(R_Pro+Z_1+Z_2)+(DC HV)/(R_Pro+R_3+R_4), whereinZ_1=((1/(j2πfC_1)+R_1)*R_3)/((1/(j2π[(fC)]_1)+R_1)+R_3), andZ_2=((1/(j2πfC_2)+R_2)*R_4)/((1/(j2π[(fC)]_2)+R_2)+R_4).